A new simple concept for the stoichiametrical funclionalization of nanoparticles based on free radical polymerization of vinyl protected nanoparticles is presented. To demonstrate this concept 2-bis(4-vinylphenyl)disulfane was synthesized and used in the synthesis of gold nanoparticles leading to 4-vinylthiophenol functionalized nanoparticles. Simple free radical polymerization of these particles initiated by 4,4'-azobis-(4-cyanopentanoic acid) delivered nanoparticles with a single carboxyl group. These monofunctionalized gold nanoparticles were utilized for chemical preparation of gold nanoparticle dippers as well as for construction of gold nanoparticle arrays via binding to polyallylamine.